cmd/hiveview: limit log bytes in suite view

It was already limited to a certain number of lines, but that's not enough when
the test outputs very long lines.

cmd/hiveview/assets/lib/app-suite.js

@@ -378,9 +378,12 @@ function formatTestDetails(suiteData, row) {
         let spinner = $('<div><div class="spinner-grow text-secondary" role="status"></div>');
         $(container).append(spinner);
 
+        const testlogMaxLines = 25;
+        const testlogMaxBytes = 2097152;
+
         let url = routes.resultsRoot + suiteData.testDetailsLog;
         let loader = new testlog.Loader(url, d.summaryResult.log);
-        loader.headAndTailLines(25).then(function (log) {
+        loader.headAndTailLines(testlogMaxLines, testlogMaxBytes).then(function (log) {
             spinner.remove();
             formatTestLog(suiteData, d.testIndex, log, container);
         }).catch(function (error) {

cmd/hiveview/assets/lib/testlog.js

@@ -56,7 +56,7 @@ function countLines(text) {
 }
 
 const NEWLINE = 10;
-const LOADER_CHUNK_SIZE = 32768;
+const LOADER_CHUNK_SIZE = 262144;
 
 // Loader provides incremental access to log files.
 export class Loader {
@@ -99,7 +99,7 @@ export class Loader {
 
     // headAndTailLines returns up to n lines from the beginning and
     // end of the log.
-    async headAndTailLines(n) {
+    async headAndTailLines(n, maxBytes) {
         var head = [];
         var headEndPosition = 0;
         var tail = [];
@@ -108,7 +108,8 @@ export class Loader {
         let eofReached = await this.iterLines(function (line, offset) {
             headEndPosition = offset;
             head.push(line);
-            return head.length < n;
+            let tooMuchData = maxBytes && offset > maxBytes && head.length > 0;
+            return head.length < n && !tooMuchData;
         });
         if (eofReached || head.length < n) {
             return {head, tail};
@@ -117,13 +118,16 @@ export class Loader {
         // Now read from tail. This stops when the read enters the
         // region already covered by the head.
         let linkWithHead = false;
+        const totalSize = this.length;
         await this._iterTailLines(function (line, offset) {
             if (offset < headEndPosition) {
                 linkWithHead = true;
                 return false;
             }
             tail.unshift(line);
-            return tail.length < n;
+            let tailSize = totalSize - offset;
+            let tooMuchData = maxBytes && tailSize > maxBytes && tail.length > 0;
+            return tail.length < n && !tooMuchData;
         });
         if (linkWithHead) {
             head = head.concat(tail);